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NUTR 344 > Nutrition and cancer > Flashcards

Nutrition and cancer Flashcards

1
Q

What is the leading cause of death in developed countries?

A

cancer

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2
Q

What is the main risk factor for cancer?

A

Age Other big factors include environmental factors, including diet

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3
Q

Nutritional factors may contribute to about __% of tumors

A

Nutritional factors may contribute to about 30% of tumors

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4
Q

What is cancer?

A

uncontrolled growth of abnormal cells in the body

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5
Q

characteristics of cancerous cells

A

– Escape normal growth signals

– Can replicate indefinitely, can form tumors

– Can avoid programmed cell death (apoptosis)

– Can alter energy metabolism

– Can avoid immune surveillance

– Can invade other tissues (metastasis)

– Can develop a blood supply (angiogenesis)

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6
Q

Synonyms of carcinoma

A

malignant tumors, neoplasms, carcinoma

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7
Q

What are benign tumors?

A

not cancerous, do not invade and metastasize

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8
Q

What is the first stage of cancer formation?

A

the process starts with alteration of the gene
DNA is altered
can be from virus, radiation, chemicals
this leads to initiation cell with damaged DNA

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9
Q

Do cancers develop 100% of the time when cell’s DNA is altered/intiation cell is created?

A

we all have some initiated cells, but we also have defences against replication of such cells
defences can be deactivated and cells will differentiate

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10
Q

What are the changes that occur, leading to development of intiatied cell?

A
  • Activation of protooncogenes
  • Inactivation of tunour-suppressor genes
  • Inactivation of genoic stability genese
  • Defects in growth control
  • Defects in terminal differentiation
  • Resistance to cytotoxicity
  • Defects in programmed cell death
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11
Q

What are the 3 steps of cancer development?

A
  1. Initiation
  2. Promotion
  3. Progression
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12
Q

What are the factors that can affects the way genotype is expressed in the phenotype?

A

Penetrance

Epigenetics

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13
Q

Define mutation

What are the possible sources?

A

structural change in the base pair sequence of DNA

Sources:

– Inherited: eg. BRCA1 gene ↑ risk of breast and ovarian cancer
– Due to exogenous factors e.g. radiation, chemicala, viruses

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14
Q

What is penetrance

A

Penetrance in genetics is the proportion of individuals carrying a particular variant (or allele) of a gene (the genotype) that also express an associated trait (the phenotype).

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15
Q

What role can SNPs play in cancer?

A

Single nucleotide polymorphisms (SNP): may affect the response to exposures

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16
Q

What is the most common type of polymorphisms?

A

SNPs

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17
Q

Polymorphisms vs mutations

A

Polymorphisms are weaker but more common than mutations

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18
Q

What do Epigenetic changes affect?

A

affect gene structure, function and expression

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19
Q

What are the common types of epigenetic changes?

A

– DNA methylation (hypermethylation of the promotor region of tumor suppressor genes → silencing)

– Acetylation of the histones → affects chromatin folding

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20
Q

Nutritional genomics and proteomics =

A

interactions between diet and genes and their products

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21
Q

diet inclued bioactive components such as __ but also __

A

diet inclued bioactive components such as nutirents but also non-nutrients

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22
Q

What is the largest effect on genes of a diet?

A

the largest effect being on epigenetics and translation to mRNA and protein
as well as post-translation impact that affect structure and function of protein

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23
Q

How can bioactive food components affect genes?

A
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24
Q

How can food increase and decrease oxidative damage to DNA?

A

– Increased by carcinogens found in foods, polyunsaturated fatty acids, iron

– Decreased by antioxidant nutrients (Vit C & E ) or cofactors in antioxidant enzymes (selenium, copper)

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25
Q

Folate and DNA link

A

Direct role of folate in DNA synthesis, repair and methylation

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26
Q

Aspects of the cell cycle that can be affected by bioactive food components

A
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27
Q

Possible causes of cancer

A

diet and obesity combined-> 1/3 of effects

diet-> 10-20%

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28
Q

• It is estimated that nearly 1 in _ Canadians will be diagnosed with cancer in their lifetime.

A

• It is estimated that nearly 1 in 2 Canadians will be diagnosed with cancer in their lifetime.

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29
Q

How has the number of cancer cases diagnosed each year has been changing?

A

The number of cancer cases diagnosed each year has been increasing because of the growing and aging population. When the effect of age and population size are removed, the risk of cancer has been decreasing.

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30
Q

Most common types of cancers in males and females

A

Males: prostate, lungs, colorectal

Females: breast, lungs, colorectal

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31
Q

Is inicidence/mortality higher in males or females

A

both are higher in males

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32
Q

What is the deadliest type of cancer? Why?

A

lung cancer is the deadliest cancer in both sexes
it is because this type is typically diagnosed late
no specific treatment

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33
Q

Cancer ourcomes and incidence in relation to age

A

Older people are more likely to be diagnosed with cancer and are more likely to die

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34
Q

Trends in cancer mortality

A

mortality has decreased significantly
cancer is now seen as a chronic disease

35
Q

Why is lung cancer related mortality and incidence decreasign?

A

lung cancer mortality and incidence is decreasing due to public health measure of anti-smoking

36
Q

Trends by cancer type in male population

A
37
Q

Trends by cancer type in female population

A
38
Q

Most common types of cancer for 0-14 yo

A

Leukemia

CNS

Lymphoma

39
Q

Most common types of cancer for 15-29 yo

A

Thryoid

Testis

Hodgkin lymphoma

40
Q

Which provinces in Canada have the highest cancer death and incidence?

A
  • Nunawut- has low incidence and high mortality, this is due to less access to medical care
  • Newfoundland
  • Nova Scotia
41
Q

Are cancer rates higher in developed or underdeveloped countries?

A

Higher cancer rates are seen more in developed countries-> proves that cancer is majorly dependent on environmental reasons (diet, smoking, lack of activity, obesity, lack of exercise)

42
Q

Cancer incidence in developed vs. developing countries

A

Developing countries: oesophagus, liver

liver cancer rates have to do with infections by hepatitis in developing countries
stomach cancer is caused by food toxins (e.g afflotoxins in grains and cereal) in developing countries

43
Q

Design of studies addressing diet and cancer (4 types)

A
44
Q

Limitations of studies addressing diet and cancer

A
45
Q

Which method is often used to collect dietaty intake data? Why?

A

FFQ → represent usual diet over long periods, adequate for large populations

46
Q

Are biochemical markers of nutrients useful in research?

A

Biochemical indicators may be useful for some nutrients (serum oxidative markers, 25(OH)D, …) but not for others (total fat, fiber, sodium, retinol…)

47
Q

How is systematic reviews and meta-analysis limited?

A

→ limited by possibility of selective publication of positive results (publication bias), difficulty in combining dietary data and control of covariates.

48
Q

Summary of Recommendations American Cancer Society

A
  • Achieve and maintain a healthy weight throughout life
  • Be physically active
  • Eat a healthy diet, with an emphasis on plant foods
    • Choose foods and drinks in amounts that help you get to and maintain
    • Limit how much processed meat and red meat you eat
    • Eat at least 2.5 cups of vegetables and fruits each day
    • Choose whole grains instead of refined grain products
  • If you drink alcohol, limit your intake
    • Drink no more than 1 drink per day for women or 2 per day for men.
49
Q

Obesity and cancer risk

A
  • higher prevalence of certain cancer in obese people- breast, uterus, colon and kidney
  • to some extent: gallbladder, pancreas
  • lung cancer patients are typically thin as they were smokers, but now there are more obese clients
  • obese women have higher risk of breast cancer as the adipose tissue acts as the source of estradiol
50
Q

How is energy balance related to cancer?

A

The rate of cell division is influenced by energy balance and growth rates → could ↑ replication of initiated cells

51
Q

How is excess weight connected to cancer mortality

A

Excess weight contribute 14% to 20% of all cancer mortality in the US

52
Q

Mechanism of obesity and increased cancer risk

A
  • Levels and metabolism of hormones (e.g. insulin, estradiol )and growth factors (IGF-1)
    • obese women have higher risk of breast cancer as the adipose tissue acts as the source of estradiol hyperinsulinemia linked to obesity (insulin acts as a growth factor) promotes cancer growth
  • Effects on inflammation and immune function
  • ↑reflux-> ↑risk of esophagus cancer
    • more reflux in obese people
53
Q

What is the impact of energy restiction on cancer

A

Energy restriction reduces development of cancer in experimental models

– The most consistent and strongest effect of diet in animal studies
– Pioneer studies in the 1950s: ↓30% energy intake=↓90%mammary tumors

54
Q

How is weigt loss, insulin and cancer connected?

A

Modestweightlossimprovesinsulinsensitivityandhormone metabolism, thus leading to decreased cancer risk

55
Q

Dietary fat and cancer

A
  • Several animal studies showed that diets high in fat promote tumor growth, but dependent on total energy intake
  • Large international differences in breast, colon, endometrium, prostate CA correlate with animal fat intake per capita.
  • fat itself is not linked to cancer, its connection is due to the caloric value (if its excessive)

But

  • In breast and colon CA
    – Pooled analyses of prospective studies showed no association – Intervention trials of low-fat diet → do not support a benefit

– no support of an association with fat (either poly, mono or saturated) that is independent from energy intake

  • thus the type of fat doesn’t matter
56
Q

Cancer and sugar

A
  • As for excess fat, excess sugar may indirectly increase cancer risk by promoting excess weight
  • Suger increases energy intake without providing any of the nutrients that reduce cancer risk (empty calories)
  • Refined sugar = brown sugar = honey = maple syrup in terms of calories
  • Recommendation: limit food and beverages of low nutritional value
57
Q

For breast, colon, endomethium and prostate, benefits of exercise are __ effects on body weight

A

For breast, colon, endomethium and prostate, benefits of exercise are independent from effects on body weight

58
Q

Consume a healthy diet, with an emphasis on __

A

Consume a healthy diet, with an emphasis on plant foods

59
Q

Dietary patterns that are connected wiht higher/lower cancer risk

A

– Individuals who eat more processed and red meat, potatoes, refined grains, and sugar-sweetened beverages and foods are at a higher risk of developing certain cancers

– whereas a diet that contains a variety of vegetables and fruits,whole grains, and fish or poultry or that is lower in red and processed meats is associated with a lower risk

Patterns do not indicate which component is more important

60
Q

Healthy dietary patterns are associated with decreased risk of _

A

Healthy dietary patterns are associated with decreased risk of cancer, CVD and all cause mortality.

61
Q

What is the type of cancer associated with hihg intake of red and processed meat?

A

associations with colorectal CA

– From meta-analysis: 12-17% increase in (probable) risk of colon CA with 100g -increment of red meat intake daily;

49% increased risk (convincing) with 25 g-increment of processed meat daily

62
Q

Potential mechanism of red meat and cancer

A

– Preservatives (nitrites + salt) -> nitrosamines (known carcinogens)

– Cooking at high temperature e.g. frying, broiling, grilling → polycyclic aromatic hydrocarbons and heterocyclic amines (known carcinogens)

– Heme promotes the formation of N-nitroso compounds (nitrosamine)

– Animal fat? May promote formation of secondary bile acids

63
Q

Overall recomendation for read meat and cancer?

A

Red meat is nutrient dense>recommend not every day, limit portion size and mode of cooking that avoids charring

64
Q

Why are fruits and veggies reccomended?

A

– contain vitamins, minerals, fibres and many phytochemicals with potential anti carcinogenic properties (carotenoids, terpenes, sterols, indoles, phenols)

– Diet rich in F&V may help maintaining healthy weight

– recent large prospective studies found weak associations with lung, upper

GI and colorectal CA, and inconsistent with other CA

65
Q

Some promising veggie-nutrient specific associations

A

– Lycopene-containing foods and prostate CA

– Cruciferous vegetables and several CA sites

– Allium vegetables and stomach CA
– Folate-rich F&V and colon CA

66
Q

B-carotene, Vit C and E, selenium supplement benefits

A

potential roles in reducing cancer risk through antioxidant properties by neutralizing reactive oxygen species (ROS) that cause DNA damage.

But, epidemiological studies and intervention trials have shown no benefits of providing these isolated nutrients in supplements

67
Q

Select trial outcomes

A

Se+ vit E supplements (SELECT trial): no effect on prostate CA, perhaps ↑ risk

68
Q

Are anti-oxidant supplements recommended?

A

Antioxydant supplements not recommended; consume whole foods

69
Q

Why choose whole grain instead of refined?

A

Sources of fibres, vitamins and minerals

70
Q

Proposed mechanisms of fibres and lower GI cancers:

A

– dilute or bind potential carcinogens, limit contact with mucosa by speeding transit, alter colonic flora, reduce pH, serve as substrate to flora producing short-chain fatty acids, e.g. butyrate which has anti-proliferative effect.

71
Q

Case-control vs short-term study results about fiber

A

Case-control studies initially supported the protective hypothesis but short-term intervention studies did not

72
Q

Recent dose-response meta-analysis of prospective studies on fiber conclusions

A

– dietary fiber intake was inversely associated with colon CA risk

– Panel conclusion: dietary fibers probably protects against colon `CA

73
Q

Fiber may also contributed to reduce cancer risk of other CA through __

A

Fiber may also contributed to reduce cancer risk of other CA through maintenance of healthy weight

74
Q

How is alcohol and cancer related

A

Known cause of CA of the oral cavity, pharynx, larynx, esophagus, and liver, especially when combined to cigarette smoking- synergetic effect

– Proposed mechanism: direct contact and toxicity in the liver

75
Q

Which cancer risk is increased by alcohol?

A

– Breast CA: 10-12% higher risk with each drink/day

– Colon CA: 40% higher risk with 3drinks/day

76
Q

Proposed mechanism of alcohol elevating cancer risk

A

– Production of acetaldehyde-> DNA damage
– For breast CA, alcohol may increase estrogens levels

-> total intake is important, not type of alcohol

77
Q

Dairy products and cancer

A
  • high milk and dairy consumption is associated with↓ risk of colon CA (also benefits from calcium supplements, possibly vitamin D) (level of evidence = probable)
  • Some studies suggested an association between dairy product intake and ↑ risk of prostate CA (also see calcium), but recent dose-response meta- analysis showed no association for non-advanced, advanced and fatal prostate CA.
78
Q

calcium and cancer

A
79
Q

Vit D and cancer

A
80
Q

level of evidence: convincing

  • decreased risk
  • increased risk
A
81
Q

level of evidence: probable

  • decreased risk
  • increased risk
A
82
Q

For whcih diet elements is research still ongoing?

A

vitamin D, turmeric and other spices

83
Q

Limited-suggestive level of evidence

  • decreased risk
  • increased risk
A
84
Q

Limited-no conclusion level of evidence

  • decreased risk
  • increased risk
A

NUTR 344 (22 decks)

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